docs: add BrowserManager → Extension communication channels

[vringar]

Summary

• Adds two missing rows to the Communication Channels table in Architecture-Internals.md: config file (browser_params.json) at startup and TCP socket (ClientSocket) per-visit
• Adds a new "BrowserManager → Extension Details" subsection explaining both channels (config read by feature.ts, socket messages received by loggingdb.ts)

Test plan

• Verify rendered markdown table alignment looks correct
• Cross-check channel descriptions against source code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 62.16%. Comparing base (58218c7) to head (be4f85d).

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1142   +/-   ##
=======================================
  Coverage   62.16%   62.16%           
=======================================
  Files          40       40           
  Lines        3898     3898           
=======================================
  Hits         2423     2423           
  Misses       1475     1475           

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